Jacob Trouba landed an elbow hit to the head of Evan Rodrigues and after handing him a five-minutes penalty, which automatically gets under review at the Department of Player Safety, refs changed their minds and reduced the penalty to a minor one.
If the NHL's DoPS decides to punish Trouba, we should know more about the situation later today. However, with only a two-minute penalty, we can expect that no consequences will be handed out to him. It that's what ends up happening, the Panthers will likely decide to seek revenge on their own, tomorrow, before game four.